Door mechanism



April 1, 1930. 0115 1,752,806

DOOR MECHANISM Filed July 16, 1925 B Q Q VN\. O Q

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Patented Apr. 1, 1930 UNITED STATES. PA ENT omen mm N. ears, or

scnmmcmnvfnnw YORK, nssrenoairo GENERAL nLEornIc comrm, A com'oaarron or N W YORK noon mncnnmsm Application filed July 16,1925. Serial No. 44,105.

' My invention relates to door mechanism and has for its object simple, reliable and efficient means for operating doors which i must be lifted in whole or in part in carrynames.

inglout the opening and closing operation. 1 y invention has particular appl1cat1on 1n the openin and closing of heavy doors which are movab e vertically, such as are'used, for example, on various types of ovens and fur- In carr ing out my invention I provide co'unterbalhncing' means "for, the door, A, the effect of which varies with the osition of the door in such manner that t e door is secured in either the open or the closed positions, and whereby the height of the mechanism is materially reduced. My inventionalso comprehends operating mechanism comprising a lever having a varying leverage which is greatest when the door is in either the closed or the open position.

For a more complete understanding invention reference'should be .had to the accompanying drawing in which Fig. 1 is a front elevation view of door mechanism embodyin m invention; Fig. 2 is a fragmenta side eflvation view of the device shown in ig. 1; while Figs. 3 and 4' are detail views showing features of construction.

Referring to the drawing, I have shown my invention in one form as applied tothe vertical door 10 of a furnace 11 which may be an electric furnace; The door 10 is movable vertically, and is provided with flanges 12 and 13 on its sides which move in vertical "guides 14 and 15 secured to the front wall of the furnace. This door may be lifted by means of two chains 16 and 17 which pass over sheaves 18 and 19 and are secured at of my pf the door. which, in the form shown, is ver- As shown in Fig." 2 the sheaves 18 and 19, which are similar in construction, are not complete circumferentially, but 5 each is shapedto have a sector shaped opening or recess24. As shown, this recess 24is substantially 90 in extent; The sheaves are otherwise symmetrically formed, and the provision of, this recess has the efiect of overbalancing the sheaves, .i. e. throwing their center, gravityftolone side of their pivoted axes, this be ng the side opposite the gaps. Furthermore,- the gaps 24 provide space for the' counterweight 20 as it ap proaches its uppermost position, as shown -F1g. 2,- in which position thedoor is in its lowermostor closed position. It will be understood that the 'two sheaves are. secured circumferentially to the shaft 21 so that the centers orsome other predetermined points of the gaps 24 will lie on a line parallel with the shaft 21. As indicated in the drawing the arrangement of the chains 16 and 17 with respect to the'sheaves is such that when the door is lowered to closed position the overbalanced weight of the sheaves act against the counterweight and thereby tend to maintain the door in closed position. Likewise, when the door is elevated to open position the overbalanced weight of the sheaves is thrown to the right of their pivot axis and, therefore, acts in the same direction as the counter weight 20 holding the door in open position.

Due to the fact that the gaps 24 provide space for the counterweight 20 it willbe observed that for the same range of movement of the counterweight the sheaves can be mounted much lower, i. e., a smaller distance above the top of the furnace than would be possible if the sheaves were whole. This 1s a ver important consideration since the require overhead space for the apparatus is very materially reduced.

In moving into these gaps it will be observed that the counterweight would ordinarily be swung slightly '1 toward the shaft 21 when the sheaves areturned to substantially the positions indicated in Fig. 2 in closing the door. In this position of the sheaves the upper sides of the gaps 24 are inclined with the horizontal and consequently the lever arm of the counterweight is no longer equal to the radius of the sheaves but is a distance somewhat less. For the purpose of'off-setting this decrease in the lever arm of the weight the radius of each sheave is increased slightly, as indicated at 19, Fi 3. In this manner the lever arm ofthe weig t is made equal to the radius of the sheaves when the door is in closed position.

In the raising and lowering of the door the shaft 21 is rotated b means of a sheave 25 which is secured to t e-shaft. A flexible connecting member, shown as a chain 26,

passes over this sheave "and has its ends secured to a lever arm 27 which is pivoted at 28 to the side of the furnace structure at a convenient height for the operator. The ends of the chain 26 are secured to the lever 27 equal distances from the pivot 28. A handle 29 is provided to facilitate the movement ofthe lever whereby the sheave 25 is rotated. This sheave 25 is preferably circumferentially whole.

The chain 26 is secured to the sheave 25 in such a position that when the door is lowered to closed position the lever 27 is inclined with the horizontal as indicated in Fig. 2, and is in a correspondingly inclined position when the door is raised to open position, the handle 29 then being uppermost. With this arrangement a relatively great leverage is obtained at the beginning of the opening and closing of the door. This leverage is provided to overcome the overbalancing action of the sheaves 18 and 19 and to overcome the friction of rest and inertia. Thus when the handle 29 is moved upward from the position shown in Fig. 2 to 0 en the door a definite movement of the ban le 29 gives only a relatively small vertical movement of the chain 26, and therefore, a relatively great leverage is obtained. However, as the lev'er27 is moved upward this leverage decreases until when in the horizontal position, the linear displacement of the handle 29 is equal to that of the chain. The same advantageous leverage conditions are obtained when the handle 29 is moved downward to close the door.

Preferably the diameter of the sheave 25 is such that less than one half its circumference is equal to the door travel, therefore the chain 26 may be secured to it by providing a cohnection at some one point. In other words, the sheave 25 need be turned only through an angle which is somewhat less than 180 in opening and closing the door so that the chain is in continuous engagement with some point on the periphery of the sheave, at which point the chain may be connected to the sheave. This relation also may and preferably does exist between the sheaves 18 and 19 and their respective chains 16 and 17. As shown, the

three sheaves 18, 19 and 25 have the same diameters, and have their respective chains connected at correspondin points 30, 31 and 32 on their peripheries. he chains are of the well known link type, and for securing them to the sheaves, the sheaves are each provided at the oints 30, 31 and 32 with axially opposite u s 33 and 34 (Figs. 3 and 4) on the inner we of their flanges 35 and 36. The space 37 between the ends of these lugs is adapted to receive freely a link edgewise, i. e.,' placed'perpendicular to the axis of the sheave. This forms a very simple mechanical connection which allows the chain to be freely removed from the sheave and also provides for a fairly fine adjustment which is from link to link.

While I have described by invention as embodied in concrete form and as operating in a specific manner in accordance w1th the rovisions of the patent statutes, it shoul be understood that I do not limit my invention thereto, since various modifications thereof will suggest themselves to those skilled in the art without departing from the spirit of my invention, the scope of which is set forth in the annexed claims.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. Operating mechanism for doors comprising a sheave operatively connected to said door, a manually pivoted operated lever arm, a chain passing over said sheave having its ends secured to said arm, and a connection between said chain and said sheave, said chain and sheave being so arranged with respect to each other that the leverage of said arm varies with the position of the door.

2. Operating mechanism for doors comprising a sheave operatively connected to said door, a pivoted operating lever for said sheave, a flexible connecting member passing over said sheave connected to said lever, a connection between said connecting member and said sheave, said lever being inclined with respect to said connectin member when the door is closed, and a ban le connected to said lever whereby a predetermined operating force may be applied to said lever at right angles thereto in any position of the lever.

3. Operating mechanism for doors comprising a sheave operatively connected to said door, a pivoted operating lever for said flexible connecting member passing over said sheave connected to said lever adjacent the ends thereof, a connection between said connecting member and a single point on'the 5 periphery of said sheave, said connection being at sucha point. on said flexible connecting member that said lever is inclined with respect to said connecting member when the door is in either the open or closed' position, and a handle on said lever whereby a predetermined operating force may be applied to said lever at right angles thereto in any pm sition of the lever.

5. Operating mechanism for vertical doors comprising a sheave mounted above said door, achain passing over said sheave having one end secured to said door, a counterweight secured to the other end of said chain, a second sheave sec redto the first, a centrally pivoted manuahy operated lever, a flexible connecting member passing over said second sheave having its end secured to said lever, said connecting member being secured to said sheave at such a point that said lever is inclined with respect to said connecting member when the door is in either open or closed position, so as to give an-operating force applied at right angles to said lever an ingreased leverage to start the movement of the oor.

6. Operating mechanism for vertical doors comprising a shaft, a sheave on said shaft, a chain secured to said door passing over said sheave, a counterweight on the end of said chain, a second sheave secured to said shaft, an operating chain secured to said sheave, a centrally pivoted lever secured at its ends to said operating chain, said lever being arranged to be inclined with respect to said chain when the door is in either open or closed position, and a handle connected to said lever whereby a predetermined operating force may be applied to said lever at right angles thereto in any position of the lever.

7. Counterbalancing mechanism for doors comprising an unbalanced sheave, a flexible connecti'ngmember passing over said sheave having one end secured to said door, and a counterweight secured to the other end of 50 said connecting member, said sheave being -so arranged that its unbalanced weight tends to secure the door in either the open or closed position.

8.. Counterbalancing mechanism for ver- 5 tical doors comprising an unbalanced sheave A mounted above said door, a cham passing over said sheave having one end secured to said door, and a counterweight secured to the other end of said connecting member, the circumference of said sheave being substantially greater than the travel of said door and said sheave being otherwise so arranged that its unbalanced weight tends to secure the door in either the open or closed position.

9. Counterbalancing mechanism for doors said sheave havin comprisin a sheave having a circumferential recess, a exible connecting member passing over said sheave having one end secured to said door, and a counterweight secured to the other end of said flexible connecting memher, said parts being so arranged that when the door is in one extreme position said counterweight lies in said recess.

10. Counterbalancing mechanism for doors comprising a sheave mounted above said door, said sheave having a circumferential recess whereby said sheave is unbalanced about it axis, a chain passing over said sheave having one end secured to said door, and a counterweight secured to the other end of said chain, said sheave being so arranged that when the door is closed the unbalanced weight of said sheave is in opposition to said counterweight and said counterweight lies in said recess.

11. Operating mechanism for vertical doors comprislng an unbalanced sheave mounted above said door, a chain passing over one end secured to said door, a counterweight secured to the other end of said chain, a second shears. connected to turn with the first, an opefiatting lever, a chain passing over said second sheave having its ends secured to said lever,said parts being so arranged that the unbalanced weight of said sheave tends to hold the door in either the open or closed position and the leverage of said lever is greatest when the door is either the open or closed position.

12. Operating I" mechanism for vertical doors comprising aF-sheave mounted above said door having a; sector cut away forming a circumferential recess whereby said sheave is unbalanced about its axis, a chain passing over said sheave having one end secured to the door, a counterweight secured to the other end of said chain, a second sheave connected to turn with the first, an operating lever, a chain passing over said secondsheave having its ends secured to said lever adjacent to ends thereof, the circumferences of said sheaves being substantially greater than the travel of the door, and connections between said chains and predetermined points on the peripheries of said sheaves respectively, whereby the unbalanced wei ht of said sheaves tends to secure the door in either the open or closed position and .whereby the leverage of said lever is greatest when the door is in either open or closed position.

13. Counterbalancing mechanism for doors comprising a sheave having a circumferential recess, a flexible connecting member passing over said sheave having one end secured to said door, and a counterweight secured tothe maintain a given leverage when said counterweight hes 1n said recess.

osition, the radius of said sheave Y gradua ly increasing adjacent said recess to 14. Counter-balancing mechanism for doors comprising a sheave mounted above said door provided with a circumferential recess, a chain passing over said sheave having one end secured to said door, a counterweight secured to the other end of said sheave-arranged to lie in said recess when the door is in one extreme position, the radius of said sheave being gradually increased adjacent said recess to compensate for the tendency of said counterweight to swing toward the axis of said sheave when it moves in said recess, whereby a given leverage is maintained for said counterweight.

In witness whereof I have hereunto set my hand this 15th day of Jul 1925.

AL ERT N. 0TIS. 

